Emerging Infectious Disease leads to Rapid Population Decline of Common British Birds

Emerging infectious diseases are increasingly cited as threats to wildlife, livestock and humans alike. They can threaten geographically isolated or critically endangered wildlife populations; however, relatively few studies have clearly demonstrated the extent to which emerging diseases can impact populations of common wildlife species. Here, we report the impact of an emerging protozoal disease on British populations of greenfinch Carduelis chloris and chaffinch Fringilla coelebs, two of the most common birds in Britain. Morphological and molecular analyses showed this to be due to Trichomonas gallinae. Trichomonosis emerged as a novel fatal disease of finches in Britain in 2005 and rapidly became epidemic within greenfinch, and to a lesser extent chaffinch, populations in 2006. By 2007, breeding populations of greenfinches and chaffinches in the geographic region of highest disease incidence had decreased by 35% and 21% respectively, representing mortality in excess of half a million birds. In contrast, declines were less pronounced or absent in these species in regions where the disease was found in intermediate or low incidence. Also, populations of dunnock Prunella modularis, which similarly feeds in gardens, but in which T. gallinae was rarely recorded, did not decline. This is the first trichomonosis epidemic reported in the scientific literature to negatively impact populations of free-ranging non-columbiform species, and such levels of mortality and decline due to an emerging infectious disease are unprecedented in British wild bird populations. This disease emergence event demonstrates the potential for a protozoan parasite to jump avian host taxonomic groups with dramatic effect over a short time period

Earthworms in the diet of herring gulls (Larus argentatus) breeding on an off-shore island

Pellets of indigestible material regurgitated by Herring Gulls Larus argentatus breeding on Lady Isle, Firth of Clyde, Scotland, were collected in 2018 and 2019 and examined for earthworm chaetae. Nearly two-thirds (65.6%) of the 314 pellets came from gulls that had consumed one or more earthworms. Significantly fewer pellets (57.6%) contained chaetae in 2018, a relatively dry May to July, than in 2019 (72.0%) when rainfall was close to the long-term average for May to July. There were significant associations between the presence of large quantities of terrestrial vegetation in the pellet and the detection of large numbers of earthworm chaetae and/or fragments of terrestrial arthropods, suggesting that recent consumption of these food items is likely when pellets contain large quantities of vegetation

Spinazie komt uit een gebied tussen de Kaukasus en de Himalaya (interview met C. Kik)

The diet of Herring Gulls Larus argentatus breeding in southwest Scotland in 2018 and 2019 was investigated by analysis of regurgitated pellets. Marine food items were found in 24.2% of 314 pellets, with the major items being Norway Lobster Nephrops norvegicus (9.6% of pellets), fish (8.9%), ragworms Eunereis longissima (8.0%) and crabs (3.5%). This is the first report of the detection of the ragworm Eunereis longissima in pellets produced by gulls in the British Isles but their availability to gulls is likely to be seasonal, and their contribution to the diet is unlikely to be high unless consumed in large numbers. Although fish significantly contributed to the energy needs of the gulls, Norway Lobsters did not. A change in commercial fishing from targeting demersal fish to Norway Lobsters could, therefore, reduce the nutritional quality of food available to Herring Gulls

Analysis of Feces Samples Collected from a Wild-Bird Garden Feeding Station in Scotland for the Presence of Verocytotoxin-Producing Escherichia coli O157

Composite wild bird feces collected at regular intervals from a garden feeding station in southwest Scotland over a 3-year period were examined for verocytotoxin-producing Escherichia coli O157. One sample was positive for Escherichia coli O157. The isolate belonged to phage type 21/28 and possessed vtx(2), eaeA, and enterohemorrhagic E. coli hlyA genes

Evidence of spread of the emerging infectious disease, finch trichomonosis, by migrating birds

Finch trichomonosis emerged in Great Britain in 2005 and led to epidemic mortality and a significant population decline of greenfinches, Carduelis chloris and chaffinches, Fringilla coelebs, in the central and western counties of England and Wales in the autumn of 2006. In this article, we show continued epidemic spread of the disease with a pronounced shift in geographical distribution towards eastern England in 2007. This was followed by international spread to southern Fennoscandia where cases were confirmed at multiple sites in the summer of 2008. Sequence data of the ITS1/5.8S/ITS2 ribosomal region and part of the small subunit (SSU) rRNA gene showed no variation between the British and Fennoscandian parasite strains of Trichomonas gallinae. Epidemiological and historical ring return data support bird migration as a plausible mechanism for the observed pattern of disease spread, and suggest the chaffinch as the most likely primary vector. This finding is novel since, although intuitive, confirmed disease spread by migratory birds is very rare and, when it has been recognised, this has generally been for diseases caused by viral pathogens. We believe this to be the first documented case of the spread of a protozoal emerging infectious disease by migrating birds

Distribution of finch trichomonosis incidents in 2006.

<p>Gardens reporting at least one incident of finch trichomonosis (large red dots) and all other sites (small yellow dots) contributing to the systematic survey. The shading indicates relative incidence of trichomonosis recorded by the opportunistic survey (incidents per thousand households for each county interpolated from county centroids). The heavy lines delineate areas of High, Intermediate and Low incidence, based on the opportunistic survey data.</p

Seasonal incidence of opportunistic reports in all garden bird mortality 2001–2006.

<p>Hatched bars – winter (Dec-Feb), open bars – spring (March–May), stippled bars – summer (June–Aug) and black bars - autumn (Sept-Nov). Note break in axis indicating an unprecedented level of reporting in autumn 2006.</p

Regional change in greenfinch occurrence in gardens in response to trichomonosis.

<p>Mean reporting rate from GBW of greenfinch, chaffinch and dunnock in spring 2005/06 (filled bars) and 2007 (open bars) in areas of Low, Intermediate and High incidence of trichomonosis incidence (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0012215#pone-0012215-g003" target="_blank">Fig. 3</a>). Bars represent 95% confidence limits.</p